Installations for reprocessing spent nuclear fuel include large, so-called hot-cells to receive the materials for processing. In these large cells, which provide a shield from radiation, processing components are arranged in scaffolds or racks.
Maintenance work within the large irradiated cell must as far as possible be carried out without the need for personnel to enter the cell. Maintenance work is therefore done by movable remote handling machines.
Remotely-controlled impact wrenches moved by a crane or a power manipulator are used to release and make threaded connections in predetermined positions.
It is known to clamp these impact wrenches in a support with two suspension lugs fixed thereto. Depending on the hold of the crane hook or power manipulator, the tool is directed to the working area hanging in a vertical or horizontal position. Changing from the horizontal to the vertical position is laborious and time consuming. The power manipulator or crane travels with the tool to a depositing station, where the tool is set down and the load hook unhooked from one suspension lug. The load hook is thereupon hooked into the other lug, and the power manipulator or crane travels back to the place of use.
When changing over to a different working position, the apparatus has to be unhooked and fitted back in the other suspension lug. During the re-suspending or re-engaging operation, there is a danger that the holding device with the tool may drop down or slip out of the hook and could then be recovered only with considerable difficulty.
In DE-GM 81 30 849, it is suggested that the working position be changed more quickly by rotatably fixing the support to the suspension means by a pin. The center of gravity common to the tool and the support is in front of the axis of rotation of the pin, as seen in the working direction. The support carries a plate with a catch mounted rotatably thereon in a bearing bolt. The catch is pressed alternately against two stops by a compression spring. The suspension means includes a side plate with abutment pegs and two cams arranged thereon in a sector of a circle.
The disadvantage of this apparatus is that it has a large number of movable parts. The apparatus itself requires maintenance and repair.